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Lightweight aluminum pressure plates (Sachs powerclutch)

Hello

Just soliciting some general opinions/advice on lightweight aluminum pressure plates (not flywheels). Specifically looking at the Sachs powerclutch kit with the aluminum flywheel. I believe it is a little over 1 lb lighter than the factory unit.

I am building a 3.4 Motronic (from a 3.2) with Mahle wedge dome 98mm (Max Moritz type/single plug) P's and C's. The pistons including rings are around 40g heavier than the factory 95mm pistons w/rings. So I am interested in cutting back the total rotating mass of the engine to help it spool up to higher rpm easier, as these pistons with add around 1/2 lb. to the total reciprocating mass of the engine. I am concerned, however, about the car stalling and doing stupid stuff as my 911 is a fun street machine with occasional DE's and drives to work.

Worth it? Thoughts?

Thanks,
BG
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Old 06-13-2012, 09:51 AM
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I put one on the 2.7
Quite happy with it (Aluminum) However i can not remember where i got it.
Any weight you can take off the spinning mass is a good thing (usually)
Old 06-13-2012, 11:24 AM
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BG,

You could get some of that back shopping for Ti wrist pins. They can be had for reasonable money if you look around. There are also several shops that specialize in removing weight from pistons. Some are very good at what they do, this is not just a 1/2 inch bull nose end mill idea we are talking about. A friend had it done on 94 mm pistons and I believe they took out some 60 grams each.

Speed cost money....how fast do you want to go.

Stay tuned,

PFM
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Old 06-13-2012, 05:13 PM
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have had the old "S" alum PP w/copper face on my 914-6 since 1972 in Germany -

don't worry - it works fine on street

only problem i ever had was when i fitted an aftermarket FLAPS "rebilt" clutch disc which only lasted one day at a PCA time trial

i then b'ot a carbon-kevlar disk from Dave Shepard (GPR) and never had another problem - he prob'ly sourced it from Kennedy

.
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Old 06-13-2012, 07:18 PM
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Here is the deal on Sachs pressure plates for (older) 911s:

2.8 RSR aluminum/aluminum sprayed wear surface: 4 pounds
2.7 stock aluminum housing/cast iron plate: 8 pounds
SC stock cast iron/cast iron: 12 pounds.

I have had the 8 pounder on my SC (and with its original 2.7 motor) since 1984. No problems with idle.

I run the RSR on my track motors. I think the idle (which I have never worked hard at getting just right) could be made smooth enough for the street. And that's with an RSR lightened flywheel. I have had the RSR PPs re-flame sprayed and machined when the wear surface started showing signs of distress.

I suspect the "power" clutch is the 8 pounder.
Old 06-14-2012, 07:44 PM
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I've used this with my 3.6/915 for many years, no problems, Revs nice, stalls easy, you will like it
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Old 06-20-2012, 03:43 PM
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I noted that the contact surface of the RSR all aluminum version tends to have small cracks develop in the surface. Not a major problem for me though.
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Old 06-21-2012, 12:45 PM
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got one in my dad's 1975 911 (3.0 with 964 cams, SSI, monty), thing revs so fast and smooth! I would do it!!!
Old 06-21-2012, 01:30 PM
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Go Light - it makes the engine come alive.

I had a light wheel in my SC engined speedester auto x machine - loved it

Built a 2.4 914-4 auto x monster, S aluminum clutch and lightened wheel - I could stall it occasionally on starting up but it was really hot.

Put a 12 pound steel billet wheel in my hot rod toyota work truck, (390,000 miles) & lots of mods and i stall it frequently, but i would do it again, the engine really picks up revs nicely.

Took about a bit more than half of the mass out of the ferrari 308 wheel and have no complaints, idles smoothly, seldom stall it and the response is better, wish i could come up with an aluminum pressure plate.

My somewhat biased .02,
chris
Old 06-21-2012, 04:58 PM
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Walt,
Where have you had the all Aluminum PP refurbished?
I have a used one I just picked up that I would like to investigate a resurface with.
Thanks!
Chet
Quote:
Here is the deal on Sachs pressure plates for (older) 911s:



2.8 RSR aluminum/aluminum sprayed wear surface: 4 pounds

2.7 stock aluminum housing/cast iron plate: 8 pounds

SC stock cast iron/cast iron: 12 pounds.



I have had the 8 pounder on my SC (and with its original 2.7 motor) since 1984. No problems with idle.



I run the RSR on my track motors. I think the idle (which I have never worked hard at getting just right) could be made smooth enough for the street. And that's with an RSR lightened flywheel. I have had the RSR PPs re-flame sprayed and machined when the wear surface started showing signs of distress.



I suspect the "power" clutch is the 8 pounder.
Old 07-17-2012, 05:13 PM
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Chet

I went to Flamespray of Denver. They knew all about the general process, suggested the material to spray (some kind of stainless, though Porsche/Sachs used something else), noted it had to be machined after the spraying, etc. This was an old timey place in a large, old building with lots of big machines, though I didn't tour it or note if they had CNC stuff as well.

Alas, next time I went there, after 2008's economic downturn, the door was locked, phone not answered, and someone said they had gone out of business.

But I'd hazard a guess that there are similar places here and there. Search for "flamespray" or the like. Not the same as DLC or other modern systems, I think.
Old 07-18-2012, 07:18 PM
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I put one on my 2.7 with a fidanza lightweight flywheel and man I could tell the difference in the performance. Big change.
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Old 07-23-2012, 03:04 PM
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Quote:
Originally Posted by DohertyCM View Post
I put one on my 2.7 with a fidanza lightweight flywheel and man I could tell the difference in the performance. Big change.
Can confirm that. Same on my 930 turbo
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Old 07-23-2012, 11:43 PM
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I just dug out this informative thread, followed Walt's lead and found this company that seems worth a try to resurface all-aluminum Sachs pressure plates:

Aluminum Clutch Disc with Steel Coated Face - Saint Paul, Minnesota

On my end, I tried with 2 clutch rebuilding suppliers in Germany (1 was Sachs Factory clutch service) but without success.

cheers
Jan

Last edited by Rostrenner; 01-09-2018 at 12:45 AM..
Old 01-09-2018, 12:35 AM
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Removing weight from rotating components such as the flywheel is similar to when your weed whacker runs with longer line (audibly lower rpm) , then as the line gets shorter ie. losing weight, it runs higher rpm with same power due to less mass to move around. Too much weight as some have pointed out can be detrimental to idle and other things, but at what point or 'Mendoza line' one should not cross I do not know. So light is good, but not too light I guess. I defer to Walt's answer for that....
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Old 01-09-2018, 04:48 AM
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Quote:
Originally Posted by BGCarrera32 View Post
.....I am building a 3.4 Motronic (from a 3.2) with Mahle wedge dome 98mm (Max Moritz type/single plug) P's and C's. The pistons including rings are around 40g heavier than the factory 95mm pistons w/rings. So I am interested in cutting back the total rotating mass of the engine to help it spool up to higher rpm easier, as these pistons with add around 1/2 lb. to the total reciprocating mass of the engine....

Thanks,
BG
Bee,
Are you sure of your piston weights? The standard 3.2 Mahle pistons are listed at around 620 grams each and the Mahle Motorsport 98mm 10.3 to 1 pistons I have are 470grams each. I acknowledge you have MM pistons but surely the weigh difference wouldn't be much?
Old 01-10-2018, 01:50 AM
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LV - I am not sure you can have a flywheel which is too light on a race car motor. I've got a Tilton 5.5" two disk clutch on my 2.8 motor. Nobody complains about the car not running well with these. Entirely impractical for the street because you can't slip it. Well, you can but it won't last if you do. Instead you give it some gas and get right off the clutch. Not like a sidestep crazy drag race start, but not smooth like we are used to with our manual transmissions. Plus you get a smoother idle with a heavier flywheel/clutch etc combination - that's kind of the purpose of the flywheel.

World of Outlaw and similar sprint cars don't have a clutch, do they? They are direct drive - put it in gear (the only gear) and you get a push start out of the paddock. Of course, the other rotating masses and the wheels have a flywheel effect when the car is moving.
Old 01-15-2018, 10:54 PM
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Agree with Walt that the lighter, the better for race clutch and flywheel. For purpose built racecars I believe Tilton makes 4.5" diameter on their carbon clutches. They'd probably go smaller if the clutch would last. Once the car is moving, any weight in the clutch/flywheel only hurts. Totally different story for a street car, of course.

Walt- I believe you're right that sprint cars are still direct drive (no clutch), and require push start. I suppose they just change the ring and pinion ratio for long vs. short tracks!

Scott
Old 01-16-2018, 03:53 AM
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Fidanza flywheel

Hi
Sorry I am going to stick with stock set up...Thanks

Last edited by frankoporsche; 01-30-2018 at 07:40 PM..
Old 01-30-2018, 03:44 PM
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SPEC stage 3+ clutches seems like a good next step up from a Sachs performance clutch
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Old 01-30-2018, 07:18 PM
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